A conventional shower head is shown in FIG. 6. The conventional shower head (70) includes a covering shell (71), a position base (72), a plurality of spraying heads (73), a metal cover (74) and a control handle set (75), wherein a connecting unit (711) (namely universal connector) is located at an upper portion of the covering shell (71) to connect to a water source. A lower portion thereof has an opening (712) that is used to receive the position base (72) and spraying heads (73) and sealed with the metal cover (74). An installation hole (713) connecting to an inner space of the opening (712) is disposed at one side of the periphery thereof. The position base (72) has a flat board (721), and a tube (722) extends upwards from center of the flat board (721), and a hanging base (723) has an elongated hole (724) at center thereof. A plurality of C-shaped hanging slots (725) are circularly disposed at the periphery of the flat board (721). The spraying head (73) engages with a plurality of hanging slots (725) through a recessed groove (731) at an upper section of the outer periphery, so as to evenly circularly dispose at the flat board (721) of the position base (72). The lower portion thereof is enlarged to form a water outlet portion (732) that forms a plurality of olive-shaped water channel (733) along the surface of the water outlet portion (732). The metal cover (74) is made by copper, surface of which has a plurality of cover through holes (741) made by the mechanical process of drilling or the like. A recessed receiving space is formed at a top surface of the metal cover (74), and a guiding rod (742) protrudes upward from center of the receiving space. The handle set (75) has a control unit (751), and a connecting rod (752) eccentrically protrudes out from one end of the control unit (751), and the other end is provided for a nut (753) to lock and engage with a movable handle (754).
When it is assembled, the spraying head (73) is installed (one by one) at the flat board (721) of the position base (72), and disposed into the covering shell (71) with the position base (72) through the opening (712). When the metal cover (74) covers the opening (712), the guiding rod (742) is inserted into the tube (722), and the through openings (741) are provided for the spraying head (73) to protrude, the position base (72) and the spraying head (73) can be restricted and engaged. Also, the handle set (75) can be fastened through the nut (753) and installed on the installation hole (713). After the installation, the connecting rod (752) of the handle set (75) will be plugged into the elongated hole (724) of the position base (72), so that the movable handle (754) is operated to drive the connecting rod (752) to eccentrically rotate. Thus, the position base (72) can drive the spraying heads (73) to simultaneously move up and down, and the amount and style of the water flows from the water channel (733) can be controlled according to each person's preference by changing relative positions between the water outlet portion (732) and the through openings (741).
However, conventional shower heads may still have the following problems: (i) the precision of the through openings (741) made by mechanical processing and electroplating is difficult to control. If an error occurs during the manufacturing process, the spraying heads (73) and the through openings (741) cannot be maintain at the identical central position (see FIGS. 7 and 8) when the through openings (741) of the metal cover (74) match with the spraying heads (73). This problem would adversely affects the smoothness and uniformity of the water flow; and (ii) the entire metal cover (74) is made by copper and the manufacturing costs may remain high, and the product may not be competitive in the market. Therefore, there remains a need for a new and improved shower head that can overcome the problems mentioned above.